The resolution was the one the issue predicted -- a registry inside the
scenario -- and it is the real path rather than a stand-in, since that is what
every node after the first pulls from.
The digests are the lab registry's own, which satisfies the pinning rule: what
is required is a reference that is exact and cannot move, and one this registry
assigned is both. That was the insight that unblocked it; I had assumed the
upstream digest had to be preserved, which is what made it look impossible.
The fault worth keeping is recorded in the issue: the read-back checked that
the catalog endpoint answered by matching the substring 'repositories', which
an empty catalog also contains. It passed on a registry holding nothing. This
repository's own subject, arriving in the tooling built to catch it.
jschoubben
087a8f4144